Biology Topic
Transpiration in Plants
- Read notes
- Flashcards
- Quiz
- Confident
Study focus - 3 things
- Transpiration is the loss of water vapour from leaves
- Water moves from roots, through xylem, to leaves
- Transpiration helps move water and minerals through the plant
Section 1What transpiration is
Transpiration is the loss of water vapour from the aerial parts of a plant, mainly the leaves. Water evaporates from moist cells inside the leaf and then diffuses out through tiny openings called stomata. It happens more quickly when conditions are hot, dry, bright, or windy.
Section 2How water moves through a plant
Water enters root hair cells from the soil by osmosis. It travels up the stem in xylem vessels and reaches the leaves. As water is lost from the leaves, more water is pulled upward from the roots.
Section 3Why transpiration matters
Transpiration helps carry water and mineral ions around the plant. It also helps cool the plant when water evaporates from leaf surfaces. Without enough water movement, leaves can wilt and photosynthesis slows down.
Section 4Stomata and guard cells
Stomata are tiny pores mostly found on the lower surface of leaves. Guard cells open and close the stomata. When stomata are open, carbon dioxide can enter for photosynthesis, but water vapour can also escape.
Examples
A plant is left in the sun and its leaves begin to droop. What process may be happening faster than water uptake?
Transpiration may be happening faster than the roots can replace the lost water, so the plant loses turgor and wilts.
A leafy plant is placed in windy, dry conditions. What happens to the rate of transpiration?
The rate increases because wind removes water vapour from around the leaves and dry air keeps a steep diffusion gradient.
Now let's water it
Session runs notes to flashcards to quiz back-to-back.